The disclosure relates to a rotation unit for rock drilling, wherein the rotation unit has no percussion device. The purpose of the rotation unit is to generate the required rotation for drilling equipment to be connected thereto, at the outermost end of which equipment there is a drill bit for breaking rock. Also, axial forces are transmitted through the rotation unit. Further, the disclosure relates to a drilling unit and a method for rock drilling.
Holes can be drilled in rock by means of various rock drilling machines. Drilling may be performed with a method combining percussions and rotation (percussive drilling), or drilling may be based on mere rotation without a percussive function (rotary drilling). Further, percussive drilling may be classified according to whether the percussion device is outside the drill hole or in the drill hole during the drilling. When the percussion device is outside the drill hole, the drilling is usually called top hammer drilling, and when the percussion device is in the drill hole, the drilling is typically called down-the-hole drilling (DTH). In a top hammer drilling machine, the percussion device and the rotation device are combined into one entity, whereas in a rotary drilling machine and DTH drilling machine, there is a rotation unit which is completely without a percussion device. This disclosure is directed to such a rotation unit without a percussion device and to the use thereof.
The rotation unit includes a main shaft that is rotated around its longitudinal axis. Rotation and torque is generated by a rotating motor connected to the main shaft through a gear system. During drilling the rotation unit is fed axially by means of a feed device in the drilling direction and the return direction. Thus, the main shaft of the rotation unit is subjected to rotational and axial forces. In current solutions, durability of the main shafts and rotation units is a problem.